Correlation effects and structural dynamics in the b-pyrochlore superconductor KOs2O6

Effects of Rattling Phonons on the Dynamics of Quasiparticle Excitation in the -Pyrochlore KOs2O6 Superconductor

Frustration in the coupled rattler system KOs2O6

Starting from ab initio electronic structure results we study dynamics of potassium ions in the pyrochlore superconductor KOs2O6. An effective ionic Hamiltonian characterized by an on-site instability rattler and frustrated nearest-neighbor interaction is derived and various approximations are investigated. We show that qualitative differences in the properties of KOs2O6 and its analogs RbOs2O6...

Novel vortex distribution in the β-pyrochlore superconductor KOs2O6

By utilizing the micro-Hall probe array, we study the superconducting and the vortex states in a single crystal of KOs2O6 near the first-order transition at Tp ∼ 8 K, which is associated with a change in the rattling motion of K ions. We show that below the first-order transition, the lower critical field exhibits a distinct decrease, suggesting that the electron-phonon coupling is weakened bel...

Scanning Tunneling Spectroscopy in the Superconducting State and Vortex Cores of the β-Pyrochlore KOs

We performed the first scanning tunneling spectroscopy measurements on the pyrochlore superconductor KOs2O6 (Tc=9.6 K) in both zero magnetic field and the vortex state at several temperatures above 1.95 K. This material presents atomically flat surfaces, yielding spatially homogeneous spectra which reveal fully gapped superconductivity with a gap anisotropy of 30%. Measurements performed at fi...

Novel rattling of K atoms in aluminium-doped defect pyrochlore tungstate.

Rattling dynamics have been identified as fundamental to superconductivity in defect pyrochlore osmates and aluminium vanadium intermetallics, as well as low thermal conductivity in clathrates and filled skutterudites. Combining inelastic neutron scattering (INS) measurements and ab initio molecular dynamics (MD) simulations, we use a new approach to investigate rattling in the Al-doped defect ...